Reactive pasty two- or multi-component systems must be stored separately after their production and until their application in order to prevent premature, inadvertent reactions of the components. Cartridge systems for the application of pasty two- or multi-component systems have been known for decades. The following documents are cited for exemplary purposes, CH 669 164 A5, EP 0 607 102 A1, EP 0 236 129 A2, DE 3 440 893 A1, U.S. Pat. No. 4,690,306 A, US 2009/062808 A1, EP 0 787 535 A1, WO 2006/005 206 A1, EP 0 693 437 A1, EP 0 294 672 A, EP 0 261 466 A1, and EP 2 008 707 A1. After the cartridges are filled with reactive pastes, the cartridges need to remain safely closed until their application. The pasty two- or multi-component systems are mixed right before their application, usually through the use of static mixers. In this context, the following documents are cited for exemplary purposes, GB 1,188,516 A, U.S. Pat. No. 2,125,245 A, U.S. Pat. No. 5,968,018 A, U.S. Pat. No. 4,068,830 A, US 2003/179648 A1, EP 0 664 153 A1, and EP 0 289 882 A1. In this context, mobile plungers seal the cartridge floors and are subsequently used to squeeze out the pastes during their application. A cartridge system having a snap-in locking device on a feed plunger of a cartridge is known from EP 2 008 707 A1.
A number of solutions has been proposed for closing a cartridge head.
One simple, but very effective, principle is to close the cartridge head with a closure that can be rotated (EP 0 431 347 A1, DE 2 017 292 A1, U.S. Pat. No. 3,215,298 A). The closure is unscrewed prior to the application. Subsequently, a dispensing tube is screwed into a thread on the cartridge head or fixed through a peg system that simulates a thread. This is disadvantageous in that the user needs to perform rotational motions twice until the paste material can be expelled. Moreover, the closure may be screwed out and the dispensing tube is attached only later. In the interim between the cartridges being opened and the dispensing tube being inserted, ingredients of the pastes may evaporate, especially if the pastes contain volatile substances.
The closure that is in very common use currently in the adhesives and sealant industry is based on the wall material of the cartridge being provided to be very thin at the cartridge head such that said wall can be perforated easily. It is disadvantageous that the perforation might be associated with particles detaching from the wall and then entering the pasty material.
Polymethylmethacrylate bone cements have been in use in medicine for decades for permanent mechanical fixation of total joint endoprostheses. They are based on powder-liquid systems. Recently, polymethylmethacrylate bone cements that are based on the use of cement pastes have been proposed as well (DE 10 2007 050 762 A1, DE 10 2008 030 312 A1, DE 10 2007 052 116 A1). Thus far, no suitable cartridge systems have been proposed for said cements.
With regard to the application of bone cements for fixation of total joint endoprostheses, it is always necessary to take into consideration that the OR staff is under time pressure during these surgeries. Therefore, as a matter of principle, cartridge systems for medical applications involving the application of paste-like polymethylmethacrylate bone cements should be designed such that they are largely resistant to user errors and can be operated rapidly and safely even in stressful situations.
The methylmethacrylate monomer is an essential ingredient of paste-like polymethylmethacrylate bone cements. Said monomer evaporates readily and has a relatively high vapour pressure at room temperature. For this reason, it is essential to note with regard to the use of methylmethacrylate-containing pastes that the cartridge plungers in the cartridges may be moved and may be expelled from the cartridges in the extreme case by the evaporating methylmethacrylate upon exposure to a vacuum, such as during the de-gassing as part of ethylene oxide sterilisation.
A cartridge system that is based on packaging pasty multi-component systems in tubular bags is known from WO 2010/006455 A1. This involves inserting the sealed tubular bags into cartridges. Tubular bags are advantageous in that they are suitable for packaging pastes that contain volatile ingredients. Tubular bags made of compound materials, such as aluminium compound bags, are particularly well-suited for this purpose. The tubular bags are opened by blades that rotate along when the dispensing tube is being screwed in. The bags are cut open in the course of the rotational motion of the blades and openings in the cartridges for dispensing the content are thus provided. The pasty bag content is subsequently squeezed or pressed through these openings in the cartridges in the direction of the static mixer.
In this context, it is disadvantageous that packaging pasty materials in tubular bags and, in addition, in cartridges is quite expensive and reserved for special applications only. Moreover, it is a problem in many applications, especially in the field of medicine, that parts of the cut tubular bags may become detached and thus may enter into the pasty components and thus contaminate the mixing ware.
A cartridge system of this type is known from EP 0 431 347 A1. The system provides openings on the cartridge heads of two cartridges through which the cartridge content can be expelled. A closure that is fastened to a bracket on the cartridge heads closes the openings.
This is disadvantageous in that the closure not only is plugged into the openings, but also snapped-in in the bracket such that removing the closure requires an effort to be made. Moreover, removed from the cartridge system, the closure may get in the way or, in case it is to be used to re-close the openings, it may get lost.